U.S. and Libyan officials are giving significantly different accounts of the gunfire and rocket-propelled grenade attack on the U.S. consulate in Benghazi that killed the U.S. ambassador to Libya and three other Americans.

U.S. and Libyan officials are giving significantly different accounts of the gunfire and rocket-propelled grenade attack on the U.S. consulate in Benghazi that killed the U.S. ambassador to Libya and three other Americans.

The Obama administration says the assault was a spontaneous local reaction inspired by a demonstration that was taking place at the U.S. Embassy in Cairo against a video made in the United States slurring the Prophet Muhammad, the founder of the Islamic faith. It also contends that the attack grew out of a small protest.

A senior Libyan official says the attack was organized and planned by foreigners – some with links to al Qaida – involved a local Islamic militia, and was timed for the anniversary of the Sept. 11, 2001, terrorist attacks on the United States. Moreover, the Libyan official appeared to question whether there was a protest beforehand.

“The way these perpetrators acted and moved, and their choosing a specific date for this so-called demonstration, I think that this leaves us with no doubt that this was pre-planned, pre-determined,” Mohammad Magarief, the head of the Libyan National Congress, the recently elected interim government, said Sunday.

The drastically different versions come as the investigation into the assault still is in its preliminary stages. FBI agents who are to assist their Libyan counterparts have yet to arrive in the North African country, and the Libyan Interior Ministry official who was in charge of the investigation was fired Monday.

Both governments would have good reason to promote their version of the incident.

Libya’s factionalized and weak interim government is confronting growing violence by militias and Islamic extremist groups that refused to disarm after overthrowing the late dictator Moammar Gadhafi last year. The interim government would appear less ineffectual and feckless if the attack were a deep-rooted conspiracy by the world’s most feared terrorist network.

President Barack Obama’s claims that he has kept Americans safe from terrorism and dealt debilitating blows to the remnants of al Qaida have been centerpieces of his appeal for re-election in November. Those claims could be questioned by GOP candidate Mitt Romney and other Republicans if al Qaida is found to have planned a well-coordinated attack on such a significant date without being detected by U.S. intelligence.

The attack claimed the lives of U.S. Ambassador to Libya Christopher Stevens, who was visiting Benghazi from the capital of Tripoli, Sean Smith, an information technology specialist, and two security men, Tyrone Woods and Glen Doherty, both former Navy SEALs.

Scores of attackers firing assault rifles and rocket-propelled grenades charged the walled compound from two directions, swarmed inside and attacked the main building, setting it afire, witnesses have told McClatchy. Stevens and Smith apparently died from smoke inhalation. Woods and Doherty were shot dead protecting up to 30 U.S. staffers who had taken refuge in a nearby annex.

The consulate compound’s landlord, Mohammed al Bishari, and a 27-year-old guard, who was wounded and asked to remain anonymous, told McClatchy last week that no protest was taking place when the attack was launched at 9:35 p.m. local time. They described the assault as sudden and well-coordinated.

The assailants were carrying the black flag of a local Islamic extremist group, Ansar al Shariah, Bishari said.

Al Qaida is suspected of playing a role because a video posted on the Internet the evening before featured Ayman al Zawahiri, Osama bin Laden’s successor, calling for revenge for the death of his second in command, Abu Yahya al Libi, a Libyan cleric, who was killed in a June 4 CIA drone strike in Pakistan’s tribal region.

Two senior Republican lawmakers questioned the administration’s version of the attack, with Sen. Lindsey Graham, R-S.C., saying it “defies common sense.” He called for a congressional investigation.

“It is imperative that Congress conduct an investigation into this matter as the two scenarios are vastly different in terms of scope and depth,” Graham said in a statement on Monday. “A planned and coordinated assault points loudly to a security lapse, and the problems associated with such a scenario are much deeper than a violent riot over a film.”

“It is my belief, as stated by the Libyan president, that this was a coordinated attack by al Qaida or like-minded groups,” said Graham, a member of the Senate Armed Services Committee.

Rep. Mike Rogers, R-Mich., the chairman of the House Intelligence Committee, said he was told by Pentagon and CIA officials that they were “only moderately confident that it was a spontaneous event because there are huge gaps in what we know.”

“I think it’s just too early to make that conclusion,” he told Fox News on Sunday.

Rogers, a former FBI agent, said that the attack “seemed to be military style, coordinated,” featured “indirect fire coordinated with direct-fire rocket attacks,” and took place on the 11th anniversary of al Qaida’s strikes on the United States. The assailants also “repelled a fairly significant Libyan force that came to rescue” the consulate.

“It just has all the markings of an al Qaida-style event,” he said.

Aaron Zelin, an expert on Islamic extremist groups at the Washington Institute for Near East Policy, said he agreed that the attack was most likely planned in advance because the assailants launched a second attack on the consulate’s safe house, which U.S. officials have been referring to as the annex.

“Not only was there the attack on the consulate, but they knew where that safe house was,” he said. “They had to have some kind of reconnaissance ahead of time.”

“I think that has more to do with the anniversary of 9/11 than anything else,” he said.

He noted that Ansar al Shariah leaders have denied ordering the attack. But they didn’t condemn it, either, he said, adding that it appeared that group members were present “in their individual capacities.”

At the same time, he said there are “no known operational links” between Ansar al Shariah and any al Qaida-affiliated groups operating in the region.

Tommy Vietor, a White House spokesman, said in an email that the administration’s version is “our assessment based on the information available.”

“I can’t speak to the factual basis for statements made by Libyan officials,” he said. He declined to comment on the statements by Rogers and Graham.

Susan Rice, the U.S. ambassador to the United Nations, laid out the administration’s version on Sunday talk shows.

“Our current best assessment, based on the information we have at present, is that, in fact, what this began as, it was spontaneous – not a pre-meditated – response to what had transpired in Cairo,” she said on ABC News’ “This Week.” “We believe . . . that a small number of people came to the . . . consulate . . . to replicate the sort of challenge that was posed in Cairo. And then as that unfolded, it seems to have been hijacked, let us say, by some individual clusters of extremists who came with heavier weapons.”

A senior intelligence official who asked not to be further identified because he was not authorized to speak publicly on the subject offered a similar assessment. “Simply put, while everything is still under investigation, the available information suggests the protests in Cairo inspired what the attackers decided to do later that night in Benghazi,” the official said. “Right now, this points to a plan that was hatched opportunistically that day. Of course, if credible new information suggests otherwise, the investigation will pursue those leads.”

In contrast, Magarief, the Libyan official, told CBS News’ “Face the Nation” that the attack was “planned by foreigners, by people who entered the country a few months ago, and they were planning this criminal act since their arrival.”

The foreigners included people from Algeria and Mali, the North African country whose northern half has been overrun by Islamic militants linked to al Qaida and whose arms are thought to have come from looted Gadhafi storehouses.

In a related development, Wanif al Sharif, the deputy interior minister who was in charge of eastern Libya and headed the investigation, was fired, according to the Libya Herald, because of the attack. Sharif was the only Libyan official to publicly say that there had been a protest before the attack. He didn’t respond to calls Monday seeking comment.

Even before the assault, many Libyans had complained about deteriorating security in Benghazi, where the uprising against Gadhafi first erupted. Scores of rogue militias have been drafted by the government to provide security in the absence of a regular force, and the role of extremists, including members of Ansar al Shariah, has been controversial.

The city is divided block by block among the groups, which have kept the weapons they procured during the uprising. Many of the militias occupy bases lined with tanks and machine-gun mounted trucks and are led by self-styled colonels.

Every time there was a bombing or other attack, Sharif blamed remnants of Gadhafi’s regime, despite evidence that groups empowered by the state were behind the violence, said Michel Cousins, the editor of the Libya Herald. The attack on the compound was the last straw for Libya’s first elected government, he said.

Magarief has been a critic of the Interior Ministry before, blaming it last month for involvement in the destruction of mosques and shrines associated with the moderate Sufi strain of Islam. Interior Minister Fawzi Abdel Al handed in his resignation after Magarief’s criticism, but he rescinded it two days later, saying the threat from Islamist militants was too great for him to step down.